In a medium-sized mixing bowl, combine the chili powder, smoked paprika, onion powder, garlic powder, oregano, salt, and black pepper. Give it a good whisk to mix everything together evenly.

Drizzle the olive oil over the flank steak, ensuring it coats both sides. Then, rub half of the spice mixture over one side, pressing it in gently. Flip the steak over and repeat with the remaining spice mix. This allows all those fantastic flavors to get into the meat.

In another bowl, whisk together the freshly squeezed orange, lime, and lemon juices, along with the soy sauce, white vinegar, and brown sugar. Mix until well combined. The combination of acids and sugars will enhance the flavor of the steak as it simmers.

Lightly grease your crock pot with a tiny bit of olive oil or cooking spray. Pour half of the prepared juice mixture into the bottom of the crock pot, creating a flavor base for the steak.

Place the seasoned flank steak in the crock pot. Pour the remaining marinade over the top of the steak. Rub it around if you feel like giving it extra love.

Cover the crock pot and set it to LOW. Let it work its magic for about 6 hours. If you have time, resist the urge to open the lid while it cooks. The steam helps keep the meat tender!

Once the cooking time is up, carefully remove the steak from the crock pot and let it rest for about 5-10 minutes. This resting period helps the juices redistribute. To slice, grab a serrated knife and cut against the grain for tender slices. Finally, return the sliced steak to the crock pot and gently toss it in the juices. Time to feast!